U.S. Pat. No. 4,559,871, Kutzner et al, to which German Patent Disclosure Document DE-OS No. 33 20 638 corresponds, describes an arrangement in which two ink separating sheet metal elements in the form of ink dividing plates, are engaged by spring force directly against the circumference of a ductor roller, in order to separate differently colored inks from each other. The lateral sealing of the ink reservoir or ink sump region is obtained by engaging the separating elements against the face surfaces of the doctor blades or stripper blades. It has been found that it is difficult to obtain effective sealing of the respective compartments of the ink sump under all operating conditions, particularly when the ink is highly liquid or viscous, which is the case for example in flexo printing ink. The arrangement also does not permit the use of doctor or stripper blades which extend axially entirely across the length of the ductor roller; rather, the doctor blades must be dimensioned to match the number and length of the respective ink reservoir compartments. It has been found, additionally, that the circumferential surface of the ductor roller can be damaged by the separating sheet metal element. A ring of ink can remain on the ductor roller which, at high operating speeds, causes ink spray therefrom and, after long operating times, may leave a dried residue which is difficult to remove.